Evaporator



June 25, 1929. SHIQPLEIY EVAPORATOR Filed'Feb. 23, 1927 2 Sheets-SheetT. SHIPLEY EVAPORATOR June 25, '1929.

Filed Feb. 23, 1927 2 Sheets-Sheet 2 Patented June 25,1929.

UNITED STATES moms summer, or YORK, PENNSYLVANIA, assreNon, BY mEsNnassronnms,

TO YORK ICE MACHINERY CORPORATION,

TIQN OF DELAWARE OF YORK, PENNSYLVANIA, A CORPORA- EVAPORATOR.

Application filed February 23, 1927. Serial No. 170,894.

This invention relates to refrigeration, and

particularly to an evaporator designed for high rates of heat transfer.

In certain prior applications I have described and claimed brine coolingsystems in which the brine is circulated through a duct at considerablevelocity in contact with an evaporator through which the liquidrefrigerant is circulated either as a result of violent ebullitiontherein, or by means of a power actuated circulating pump. The eflect ofthis forced circulation is greatly to increase the heat transfer rateper square foot of evaporator surface, with a consequent reduction inthe size of the evaporator for a given heat load.

Such evaporators must be operated flooded, and since the evaporation ofthe volatile refrigerant is violent it is necessary to provide for theready disengagement and discharge of the resultlng vapor without theundue entrainment of liquid refrigerant. Unless the vapor is freelydischarged from the evaporator it becomes largely gas-bound and there isa consequent reduction of its effective surface area. I

It is a relatively simple matter to design on paper an evaporator whichofl'ers the necessary short upward flow paths for the disengaged vapor,but such designs do not lend themselves readily to construction with thematerials and methods now available, particularly when considerations ofstrength and maintained gas-tightness are taken into account. Forexample, it has been proposed to use two practically horizontal headers,the lower one being the liquid supply header and the upper the gasoff-take header, and to connect these headers by vertical tubes. Such anevaporator, could it be commercially constructed, would be almost ideal,but it has.

been found that extreme accuracy in the dimensions of the tubes 'isnecessary, and that as soon as a few tubes are put in place thestructure becomes so rigid that the positioning of the remaining tubesbecomes exceedingly diflicult, and the replacement of a defective tubebecomes virtually impossible.

The purpose of the present invention is to produce an evaporator havingthe advantages characteristic of the type just described,

without the inherent manufacturing disadvantages, and incidentallyproduce an evaporator which can be readily constructed 1n segtionscapable of ready assembly on the o Another object of the invention is toproduce a structure of this character offering a very large effectivesurface in proportion to its over-all dimensions, and so designed as 60not undul to retard the flow of brine or other liquid in contact withthe exterior of the evaporator.

Generall stated, I make use of a lower liquid hea er and an upper as orvapor header connected at one end a vertlcal chamber which serves as acom ined liquid reservoir and suction trap. By making this of sufiicientcapacity it may also serve as the main receiver of the system, in whichcase it becomes what is commonly known to the trade as a receiversuction trap. The two horizontal headers are connected by tubes whichhave a bowed, or referabl a V- shaped form, so as to combine a reatively long flow path through the tubes from the lower to the upperheader with a relatively steep flow gradient favorable to thedisengagement of vapor from the liquid. 0 i

In order to give a favorable angle of entrance of each tube into the twoheaders, the ends of the tubes are bent to reduce their obliquity to theheaders, though it is ordinarily not feasible to bend the tubes to suchan extent that they enter the headers with their axes in a line strictlvradial to the headers. These tubes are welded in place. Furthermore, theheaders are formed in sections which are connected end to end. Thus eachevaporator is made up of a plurality of sections, each sectionconsisting of a top header section, a bottom header section, and a groupof V-shaped tubes connecting the same. The nature of the joints in theheader ordinarily entails a slight interval between successive groups oftubes in a complete evaporator. This effect is avoided, so far aspossible, by the use of a. reinforced welded butt-joint betweensuccessive header sections.

A commercial embodiment of the invention is illustrated in theaccompanying drawings, in which Fig. 1 is an elevation of the evaporatorassembled.

Fig. 2 is a plan view of the same. In Figs. 1 and 2 the generaldimensions of the confining duct for the brine are indicated in brokenlines, it being uderstood that the through the header.

brine is circulated longitudinally throu h the duct so that the brineflo-w is paral el with the top and bottom headers of the evaporator.

Figr3 is a transverse section through the evaporator showing this on anenlarged scale and showing it in. position in the brine confining duct.

Fig. 4 is a detail showing the welded joint between two sections of aheader, the view being taken in longitudinal axial section The verticaldrum 6, shown in Figs. 1 and 2, serves as a receiver suction trap andextends upward above the upper header of the evaporator, and thus may,if desired, be operated to maintain a static head of liquid ammonia onthe entire evaporator. The feed line for liquid ammonia is indicated at31 and the suction line leading from the drum 6 to the compressor .isshown at 32. Extending horizontally from a point near the bottom of thedrum 6 are two parallel liquid headers 7. Parallel with and above theheaders 7, at a height determined by the vertical dimension of the ductin which the evaporator is to be mounted, are two parallel gas or vaporheaders 8. The headers 7 and 8 are made in sections connected by oints,indicated generally in Figs. 1 and 2 by the numeral 9. The constructionof the joint is shown in detail in Fig. 4, the joint proper 9 consistingof fused metal deposited by a welding process. Alinement of the twosections is secured by an internal sleeve 10 which assists in stiffeningthe joint and which enters, to some extent, into the structure of thecomplete welded oint.

Each section of each lower header 7 is connected with the correspondingsection of the corresponding upper header 8, by a plurallty of tubes 11,each of which is characterized by a bow or bend 12 which gives to thetube as a whole a bowed or V-shape. I prefer to make the bend 12 of arelatively short radius because this increases the length of the tube 11between headers and simpllfies the bending operation, but, obviously,the radius of the bend 12 may be increased, and as it is increased theform of the tube would approach a simple arc.

I do not regard the radius of the bend 12 as more than a matter ofdimension so far as the broader aspects of this invention are concerned,but for manufacturing reasons, it is believed to be simpler to use aform of tube 11 substantially as illustrated in the drawing.

Between each pair of headers 7 and 8 there are three sets of tubesarranged in three planes The axial plane of the center set passesthrough the axis of the two headers, and the "axial planes of the twoside sets are parallel with this plane and at approximate tangency-withthe sides of the headers. The spacing is such as to offer continuousclear flow paths between the groups of tubes in the different planes, asis made clearly apparent in Fig. 3. Furthermore, the overall dimensionmeasured across the outside tubes approximates, or at any rate does notmaterially exceed, the outside diameter of the headers, thus producing acompact unit for mounting in a duct of rectangular cross section.

Adjacent both ends each tube 11 is bent to afford a favorable angle ofentry into the header. The tubes are welded in place and it is thereforenot necessary that they enter in a strictly radial direction relativelyto the header. Thus tubes in the middle plane are simply bent in thisplane to a slight angle, as indicated at 13 on Fig. 1. This does notcause the tube to enter the header in a strictly radial direction, as itis not desirable to bend the tubes more than is necessary to give areasonably favorable angle of entrance. The ends of the tubes in the twoside planes are bent obliquely, as indicated at 14, the nature of thebend being apparent from an inspection of Figs. 1 and 3. The bend issuch that when viewed in cross section (see Fig. 3) the ends of thetubes enter the header in an approximately radial direction.

The ends of the tubes project into the headers, as clearly indicated at15 in Fig. 3. Because of the inclination of the entering portions of thetubes 11 to the axes of the headers 7 and 8, the refrigerant flowingoutward in the header 7, will have a natural tendency to enter the tubes11 and refrigerant vapor discharging into the header 8 from the tubeswill discharge with a component of motion in the direction of flowtoward the drum 6. This is favorable to rapid circulation of therefrigerant through the evaporator.

The upper header 8 is closed at its outer end, as shown at 16. The lowerheader 7 is provided with an extra section 17, to which no tubes areconnected. This is closed as indicated at 18, and is mounted with aslight downward inclination, as is shown in Fig. 1. The purpose of theextra section 17 is to receive and drain away from the header 7 any oilwhich may enter the drum 6. The connections 19 shown in Fig. 1 are oiltake-ofi' connections designed to remove oil from the extreme end of thesection 17. There is one section 17 for each.

of the two headers 7, and also a corresponding oil drain connection 19for each.

While the evaporator described above is suited for various uses, and nonecessary limitation to any particular field of use in the refrigeratingart is implied, the evaporator offers peculiar advantages in connectionwith brine coolers in which the brine is circulated through a confiningduct at high this is that the most violent a very heavy heat load uponthe evaporator that it is under such conditions that this evaporatordevelops its marked utility.

In Fig. 3 I show in transverse section a duct of this description. Theside walls of the duct are indicated at 20, the top at 21 and the bottomat 22. The bottom of an ordinary brine tank is indicated at 23. It willbe understood that brine is drawn from the tank and pumpedlongitudinally through this duct. The broken lines 24 in Fig. 1, and 25,in Fig. 2, indicate the approximate dimensions of a duct suitable foruse with the evaporator illustrated.

It should be mentioned that the evaporator is shown with sections brokenout and that as commonly constructed each section will usually be longerthan is shown in the drawing and the over-all length of the evap oratorwill accordingly be far greater than,

it is possible to show on a reasonable scale in a Patent Ofiice drawing.

, It is desirable that the brine flow from left to right with referenceto Fig. 1, so that relatively warm brine enters adjacent the drum 6 andthe chilled brine is discharged at the far end of the evaporatoradjacent the closed end of the headers. The reason for ebullition in theevaporator will occur where warm brine is in contact with the walls ofthe evaporator, and it is obviously desirable to have the violentebullition occur where a short flow path'for the refrigerant from and tothe drum 6 is afforded.

While'I have shown two units connected to a single drum 6, itisobviously immaterial Whether only one or a substantially greater numberof such units is so connected. Similarly there are no specific limits asto the number of tubes 11 which are connected to a single headersection. The number is de- .termined by shop facilities and erectionfacilities on the job and will vary in particular cases. The presence ofthe joints 9 necessitates short intervals between the groups of tubes 11for each section of the header (see Fig. 1) but by careful designing ofthe joints 9 it is possible minimize this interval.

What is claimed is,-

1. In' an evaporator, the combination of an upper header; anapproximately parallel lower header; and a plurality of bowed tubesconnecting said headers and nested in and substantially confined to theinterval 'between headers.

2. In an evaporator, the combination ofan upper header; an approximatelyparallel lower header; and a plurality of tubes bent on short radii toform V-shaped nesting passes between said headers, said passes ly ingbetween planes approximately tangent to the sides of said headers.

3. In an evaporator, the combination of an upper header; anapproximately parallel lower header; and a plurality of tubes bent onshort radii to form V-shaped nesting passes between said headers, saidtubes being also bent adjacent their ends so as to enter said headers ata less angle than thatmade with the header by the tube,-the tubes beingwelded in place.

4. In an evaporator, the combination of a receptacle forming a receiversuction trap;

approximately horizontal parallel upper and lower headers extendingdirectly from said trap; and tubes connecting said headers.

5. In an evaporator, the combination of a receptacle forming a receiversuction trap; approximately horizontal parallel upper and lower headersextending directly from said trap; and a plurality of bowed tubesconnecting said headers and nested in the interval between headers.

6. In an evaporator, the combination of a receptacle forming a receiversuction trap; a plurality of approximately horizontal upper headers; aplurality ofapproximately horizontal lower headers, the upper headersand lower headers being substantially parallel with each other; and aplurality of bowed tubes connecting said upper and low-' er headers andnested in the intervals between headers, said tubes bein arranged toafiord continuous flow paths iietween tubes in the direction of thelength of said headers.

7. In an evaporator, the combination of a pair of substantially parallelheaders; connections for supplying liquid refrigerant to an end of oneheader and for withdrawing refrigerant from an end of the other header;and a plurality of tubes connecting said headers and projecting at theire'n s into said headers in general directions toward the supply end ofthe first header and toward the discharge end of the second header.

8. In an evaporator, the combination of a pair of substantially parallelheaders; connections for supplying liquid refrigerant to one 'end of oneheader and for withdrawing refrigerant from the same end ofthe otherheader; and a plurality of tubes bent upon themselves, connecting saidheaders and projecting at their ends into said headers in generaldirections towards the supply end of other. signed my THOMAS SHIPLEY.

DISCLAIMER 1,7 18,313.17wmas Shipley, York, Pa. EVAPORATOR. Patent datedJune 25,

' 1929. Disclaimer filed October 18, 1935, by the assignee, York Ice Maychinery Corporation.

Hereb enters disclaimer to that part of the claims in said specificationwhich are in the ollowing words, to wit:

1. In an ova orator, the combination of an upper header; andapproximately parallel lower hea er; and a plurality of bowed tubesconnecting said headers and nested in and substantially confined to theinterval between headers.v v

2. In an evaporator, the combination of an upper header; andapproximately parallel lower header; and a plurality of tubes bent onshort radii to form V-shaped nesting passes between said headers, saidpasses lying between planes approximately tangent to the sides of saidheaders.

3. In an evaporator, the combination of an upper header; andapproximately parallel lower header; and a plurality of tubes bent onshort radii to form V-shaped nesting passes between said headers, saidtubes being also bent adjacent their ends so as to enter said headers ata less angle than that made with the header by the tube, the tubes beinwelded'in place.

'[Oflimlal Gazette ovembcr 12-, 1935.]

